Secondary air supply mechanism for filters



Jan. 1, 195.7 E. E. FOWLER SECONDARY AIR SUPPLY MECHANISM FOR FILTERS 3 Sheets-Sheet 1 Filed April 1, 1955 I l I I l IN VEN TOR.

EVANS E. FOWLER BY I ATTORNEY Jan. 1, 1957 E. E. FOWLER 2,776,024

SECONDARY AIR SUPPLY MECHANISM FOR FILTERS Filed April 1, 1955 s Sheets-Sheet 2 I5 32 '34 A 4 23 w 4 INVENTOR. s3 EVANS E.FOWLER By WW Fig.7

ATTORNEY Jan. 1, 1957 E. E. FOWLER SECONDARY AIR SUPPLY MECHANISM FOR FILTERS 3 Sheets-Sheet 3 Filed April 1, 1955 new INVENTOR. EVANS E. FOWLER ATTORNEY United States Patent SECONDARY AIR SUPPLY MECHANISM FOR ILTERS Evans E. Fowler, Louisville, Ky., assignor to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Application April 1, 1955, Serial No. 498,665

9 Claims. (Cl. 183-61) The present invention relates to dust collectors of the tubular stocking type, and relates in particular to improvements in supplying secondary air to the filter elements.

In one typical form of such filter or dust collector, one or more tubular air permeable filter elements extend between a supply header and a dust hopper, and the air to be cleaned flows from the header through the wall of the filter element, depositing dust on the inside surface thereof. Some of this dust falls into the hopper, and some dust accumulates on the interior surfaces of the filter elements. Periodically, a nozzle which traverses the filter elements, directs a stream of secondary air against the exterior surfaces of the filter elements, to dislodge dust on the interior surfaces. The present invention is directed to a structure for supplying secondary air to the nozzle.

It is an object of this invention to provide a simple, effective structure for supplying secondary air from a fixed source to the moving nozzle or blow ring.

A further object is the provision of a structure for supplying secondary air to the filter tubes which is relatively inexpensive to manufacture and is trouble free in service.

A further object is the provision of a structure for supplying secondary air to the filter tubes, which involves an improved leakage free joint between relatively reciprocating parts in the secondary air system.

The invention is described in detail in the following specification taken in connection with the accompanying drawing, illustrating a preferred embodiment by way of example, and wherein:

Figure 1 is a front elevation of a dust separator embodying the invention; parts being broken away;

Figure 2 is a side elevation of Figure 1 with parts broken away;

Figure 3 is a plan view, with part broken away, of a blow ring structure;

Figure 4 is an elevation view with parts in section, of a detail;

Figure 5 is an end elevation, with parts broken away of a blow ring structure;

Figure 6 is a fragmentary sectional view, corresponding to one taken along line VI--VI of both Figures 2 and 3, showing the high pressure air supply duct in section;

Figure 7 is an end elevation showing the mounting of the air supply duct, with parts in section;

Figure 8 is a section taken on line VIII-VIII of Fig- 2,776,024 Patented Jan. 1, 1957 Figure 10 is a fragmentary vertical sectional view showing the relationship of the high pressure inlet to the dust hopper and to the high pressure distribution tube.

Referring to the drawing, the typical filter unit illustrated comprises a frame 1 carrying a top duct or header 2 having a side inlet opening 3 for the entrance of gas to be cleaned. Downwardly spaced from the header is a bottom dust hopper 4, and a series of cylindrical filter elements or tubes 5 constructed of suitable fabric, or other gas permeable material, are connected at their tops to suitable openings in the header, and are connected at their bottoms to suitable openings in the dust hopper 4. The connections to the dust hopper are arranged to allow vertical contraction of the tubes 5, without loss of seal with the hopper. The header, dust hopper and filter elements may be constructed, for example, as described and claimed in the application of Stig G. Sylvan, Serial No. 363,322, filed June 22, 1953, now Patent No. 2,751,042, dated June 19, 1956, for Mechanical Dry Tubular-Stocking Dust Collector, etc., and as this construction forms no part of the present invention, it will not be described in greater detail.

It will be seen the tubes 5 are arranged in banks of any desired number, and the vertically slideable blow ring frame 6 is common to the bank of tubes. The frame 6 carries a plurality of blow rings to be later described. Periodically, the tubes 5 are traversed by the blow ring frame 6, and the blow rings discharge high pressure air against the tubes as they move downwardly, so as to dislodge dust from the inside surface of each tube and allow the dust to fall into the hopper.

An air inlet portion of the frame 6 (Figs. 3 to 6) comprises a generally U-shaped frame having an end wall 7 and side panels 8 and 9 with an opening 11 in each side panel. The inlet portion of the frame may be made by bending a single strip of metal into a U- shape, or as shown, by uniting a separate back panel 7 to the side panels 8 and 9. This structure is closed in by top and bottom plates 12, 13 secured in air tight relation to the back and side panels, respectively above and below opening 11. At its forward edge each plate is notched out at 14.

A shoe or nozzle 15 in the general shape of a sharp edge ellipse is formed by welding together bowed side plates 16 and 17 at the top and bottom, and if desired a middle brace bar 18 may be welded in the shoe. Each side plate of the shoe is notched out at 19. The shoe is placed within the notches 14 of the top and bottom plates so that part of the shoe overlaps these plates, and the shoe: may be welded in this position. The overlapping end of the shoe is closed by end plates 21, 22, and end plates 23, 24 close the space between the forward edges of the top and bottom plates 12, 13 at the sides of the shoe. Thus, air which enters the shoe is directed into the chamber 25 between plates 12, 13 and can flow through side openings 11.

The blow rings are constructed in units and any desired number of units may be connected together in the frame 6 to constitute a bank. As illustrated, each blow ring assembly comprises a frame 27 of generally square shape in plan, and a pair of dished plates 28, 29 are suitably secured in the frame in vertically spaced relation. The blow ring plates converge about a central opening 31 approximately the diameter of a filter cylinder, and are vertically spaced about said opening to provide a slit or nozzle 32 by which a narrow jet or stream of air is .directed against the filter tube. The space 34 between the plates provides an air distributing chamber for the nozzle, and openings (not shown), are provided through the frame 27 to connect the distributing chamber 34 with the inlet chamber 25. Thus, air introduced into nozzle member or shoe is conducted from chamber to the various ring nozzles 32 where it is discharged against the respective filter tubes. The frame 6 may have a plurality of elliptical nozzles 15 and distribution or plenum chambers 25, depending on the number of blow ring nozzles in a bank.

The arrangement by which air is supplied to the nozzle member 15 now will be described.

A tube or air supply channel 37 is mounted on the hopper, and at the top is held in place in a channel 35 by an angle plate 36 bolted to the channel 35 and air supply channel 37. As shown in Figure 8, the air supply channel comprises a vertical base wall 38, and side walls 39, 41 having flanges 45, 46 respectively which provide an opening 42 opposite wall 38. Converging flaps 43 and 44 are bolted to the flanges 45, 46, and these flaps extending substantially the full length of the channel and thus separate the opening 42 from the air supply chamber 47. The flaps are protected by suitable cover plates 48. The top of channel 37 is closed by a plate 49 which may be welded in place, and a triangular plate 51, having a slot 52, is adjustably bolted to the bottom of plate 49. This triangular plate carries horizontally spaced vertically-depending flanges 53 and 54 which embrace the top edges of flaps 43, 44.

The bottom of column 37 receives a flange 55 having a triangular internal projection 56 to which a vertical flange 57 is welded. A triangular plate 58 (similar to plate 51) is adjustably bolted to bottom flange 55 and carries vertical flange 59. The flanges 57, 59 embrace the bottom edges of the flaps 43, 44. It will be seen the flaps 43, 44, which may be made of flexible material, such as Neoprene rubber or silicone rubber, have lips 61, 62 respectively of reduced thickness. The pressure of air in supply chamber 47 holds the flaps against the outer flanges 54, 59 at the ends, and holds the lips 61, 62, together to prevent leakage of air between them.

An air inlet duct 63 extends through but is partitioned from the bottom hopper 4 as indicated at 63a. It is connected to supply high pressure air to column 37 through bottom opening 64 in the column, the connection between bottom flange 55 and the hopper top being sealed by a gasket 65.

Referring to Figures 1, 2 and 6, it will be seen that the frame 6 is guided in its vertical movement by casters 66 mounted in suitable bearings or brackets 67 in the frame 6, the casters bearing against the base plates 33 of the air channels 37. The frame 6 is positioned so that the shoe 15, which is ground to knife edges at the top and bottom, enters between the flaps 43 and 44 and the air pressure in chamber 47 holds the flaps against the shoe to prevent leakage of air around the exterior edge of the shoe. Thus, air is supplied from chamber 47 to the shoe, as the shoe 15 and blow ring frame 6 move down, and from the shoe air flows to the blow ring nozzles.

At each end of the frame 1 there is a cross bar 68 which carries sprockets 69, 71 in suitable bearings, and sprockets 72, 73 are mounted at the top of the frame 1 at each end. The blow ring frame 6 has brackets 74, 75 to which are swivelled links 76, 77 connected by a bar 78. Endless ,chains 81, 82 extend around the pairs of sprockets 72, 69, and 73, 71, respectively, and the bar 78 is connected at each end to each chain. Thus, as the chains move around the sprockets they carry frame 6 down, then up, and down again, etc. The chains are driven by a motor 83 through suitable transmission mechanism which need not be described in detail. In operation, the supply of air to column 37 may be controlled so that air is admitted thereto only when the blow ring frame is moving down, and the drive mechanism may be timed to move .the blow-ring at any suitable intervals.

The operation of the apparatus now will be described. Air to be cleaned is introduced at inlet 3, flows into header 2, and thence through filter tubes 5, depositing dust on the inner surfaces. At the proper time, secondary air under pressure is supplied by inlet 63 to the chamber 47 in column 37, and this air flows into shoe or nozzle 15 projecting between the lips 61, 62 of flaps 43, 44. The pressure in chamber 47 holds these lips against the surface of the shoe tightly enough to prevent substantial leakage therebetween, and also holds the lips together along the length of the column in sealing relation. Secondary air thus flows through shoe 15 to chamber 25 and thence to the blow ring nozzles 32, which directs the air against the outside surface of the filter tubes 5. As the frame 6 carrying shoe 15 moves downwardly, the shoe forces apart the lips 61, 62 to allow the shoe to slide downwardly, while the pressure within chamber 47 maintains the lips in sealing contact with the shoe. Thus, the blow ring frame 6 carries the blow rings down while maintaining a supply of secondary air thereto to dislodge the dust from the inner surfaces. The dislodged dust falls into the hopper 4.

When the bar 78 on chains 81, 82 reach the lower sprockets 69, 71, the frame 6 is at the bottom of the filter tubes, and at this point the supply of secondary air may be cut off by any suitable mechanism. The chains continue around the sprockets and carry the frame 6 up again toward the top, and when the frame reaches the top, the motor 83 is stopped by any suitable mechanism.

I claim as my invention:

1. In a filter, the combination comprising: at least one vertically arranged pervious filter tube; a blow ring frame carrying a corresponding number of blow nozzle means, one for around each filter tube, said frame being adapted to longitudinally traverse said tube; a generally elliptically shaped hollow inlet nozzle carried by said frame, said hollow inlet nozzle communicating with said blow nozzle means; and an air supply tube having an elongated opening covered by converging flexible flaps receiving said hollow inlet nozzle therebetween, for supplying air through said hollow inlet nozzle to said blow nozzle means.

2. A filter as specified in claim 1 wherein: said air supply tube has at its ends vertically arranged pairs of flanges embracing and sealing the ends of said flaps against escape of air.

3. A filter as specified in claim 1 wherein: said air supply tube provides a vertical track, and said blow ring frame carries cooperating guide means engaging said track in the traversing movement of said frame.

4. A filter as specified in claim 1 wherein: said blow nozzle means comprises a plurality of dished plates with an opening therethrough to receive said filter tube, said plates converging about said tube in spaced relation to form a slit ring nozzle.

5. A filter as specified in claim 4 wherein: said blow ring frame provides a plenum chamber communicating with said hollow nozzle, and with the space between said dished plates.

6. A filter as specified in claim 1 wherein: a plurality of said filter tubes are arranged in a bank; said blow ring frame carries a plurality of blow nozzles; and said hollow nozzle communicates with said blow nozzles to supply air thereto.

7. A filter as specified in claim 1 wherein: said flaps comprise a silicone rubber.

8. A filter as specified in claim 1 wherein: a plurality of endless bands pass around vertically spaced pairs of wheels at the sides of said frame; means are provided for driving said bands; and links are attached to said frame and bands, for moving said frame vertically.

9. A dust collector comprising: a filter tube vertically arranged between a tube supporting header and a dust hopper to receive dusty gas, filter that gas as it passes radially outward through the tube wall into the surround ing atmosphere and ultimately discharge the separated dust axially into the hopper; a tube-traversing reversejet blow ring providing a nozzle encircling the tube and being operative to discharge an annular jet of high pressure gas radially inward through the tube wall into the interior of the tube to dislodge dust deposited on the inner face of the tube; means for reciprocating the blow ring along the tube; a tubular gas-inlet piece projecting from said blow ring; and a stationary, vertically arranged high pressure gas supply header for supplying high pressure gas through said tubular inlet piece to said blow ring, said header having a vertically elongated section formed by inwardly converging flexible flaps which are held against each other in gas sealing position by the gas supply pressure, said flaps being positioned to receive and extend snugly around said tubular inlet piece as it travels upwardly and downwardly along the tube.

Lang May 8, 1951 Osgood et all Dec. 1, 1953 

